Loud speaker



Aug. 15, 1933. A A. THOMAS 1,922,181

LOUD SPEAKER Filed June 30 1925 3 Sheets-Sheet l yzy/ . l r INVENTOR LAug. 15, 1933. THOMAS 1,922,181

LOUD SPEAKER Filed June 50 192 3 Sheets-Sheet 2 Aug. 15, 1933. A. o s1,922,181

LOUD SPEAKER Filed June 30, 1926 3 Sheets-Sheet 3 &\

INVENTOR UNIT-ED. sm-us PATENT OFFICE 1,922,181 LOUD SPEAKER Adolph A.Thomas, hlew IforkQN. Y. Application .Iune so, 1926. serial No. 119,575as Claims. "(01. 181 -31) My invention relates to sound-reproducingapparatus, and its object is to'pro'vide a loudspeaker of combined hornand cone type, so that the "advantages of both may be realized in asingle instrum'ent of compact'construction.

Itis generally recognized by acoustic engineers, particularly in theradio field, that a loudspeaker with a single diaphragm cannot reproducethe entire musical scale with-proper tonal value. That is true of thesmall'diaphragms in horn speakers and the large diaphragms in conespeakers. It seems to be the prevailing opinion that the first type offloudspeaker gives a better reproduction of the higher register, andthat cone speakers favor the lowerregister.

In accordance with my invention I produce a loudspeaker having aplurality of diaphragms arranged to be simultaneously operated by electromagnetic mechanism. At the present time I prefer to use threediaphragms designed to respond to all notes of the musical scale withsubstantially equal fidelity anduniform intensity. At least one of thesediaphragms'is of the cone type that requires no horn for amplification.

When I employ three diaphragms; the other two are connected with anamplifying horn; These two diaphragms are of different acousticproperties. one operating best on the high register,

and the other being most eiiicient on the middle register. The largecone diaphragm reproduces best the lower frequencies, particularly thedeep bass notes. I may, however, use only one horn diaphragm. v

All diaphragmsin my combined horn and cone speaker are simultaneouslyactuated by the same mechanism. In a preferred embodiment of myinvention, a single armature of novel construction operates all threediaphragms, and the connections between those parts are so simple thatthere is practically no lost motion. vThe two horn diaphragms arearranged at right angles to the cone diaphragm and communicate with thehorn through a pair of lateral tone arms between which the cone ismounted. The resultant structure is one of unusual compactness,permitting a large cone diaphragm and a horn of considerable length tobe housed in a cabinet of comparatively small dimensions.

When I use only one horn diaphragm in combination with a cone, Iprovidea horn structure coiled upon itself to furnish an amplifyingconduit'of requisite length, andthe'cone is mounted;

within the turns-of the horn in a plane at right angles thereto. In thisembodiment I'preferito 'larly the electromagnetic actuating mechanismemploy an improved form of electromagnetic mechanism designed tooperatethe two diaphragms simultaneously but slightly out of phase with eachother. The acoustic result is a fuller and richer reproduction than ifthe diaphragms vibrated in strictunison.

The foregoing and other features and advan', tages of my invention willbe better understood from a detailed description of several embodimentsshown by way of example in the accomin full for clearness;

Fig. am a rear-view partly in section taken approximately on the brokenline 4--4 of Fig. 3; Fig.5 is a detached view on an exaggerated scaleshowing certain-structural details of the magnet and armature foroperating the two horn diaphragms and the cone diaphragm;

' Fig. 8 is a side view' of the magnetic structure shown in Fig. 5;

Fig. 7 is across-sectional detail on line 7-7 of Fig. 8, showing themounting of one of the magnet coils;

Fig. 8 is adetached perspective view on an enlarged scale, showing theconstruction and relative arrangement of the magnetic pole-pieces andthe bell-crank armature;

Fig. 9 shows a modification in which only one horn-diaphragm is used,certain parts being shown in cross-section for clearness;

Fig. 10 is a detached view in cross-section showing the polarconstruction of the actuating magnet and the mounting of the controllingcoils by which the two diaphragms are simultaneously operated;

Fig. 11 1s a cross-section on line 11-11 of Fig. 10:

Fig. 1-2 shows a face view of a preferred form of diaphragm used in theconstruction of Fig. 9; v 1

Fig. 12;

Before describing the figures in detail, I want -to 'explainthat I haveintentionally illustrated certain-parts'in exaggerated proportion,particuforthe purpose of making the drawings as clear 5 first describethe three-diaphragm speaker shown in Figs. 1-8.

The various parts that constitute the loudauy suitable construction anddesign, depending upon the size of the horn and cone diaphragm. In thepresent instance, I have shown a cabinet comprising a base 10, sides 11and aback 12. The upper part of the cabinet may be arched, as

shown at 13, and provided at the front witlra' or non-metallic materialsuitable for acoustic purposes. as those familiar with the art willunderstand. If found necessary or desirable, the inner arms 17' and 18may be steadied against vibration by a pair of brackets secured to thewalls of the casing, as diagrammatically indicated by dotted lines 28 inFig. 4. speaker are housed in a casing, or cabinet indicateda's a wholeby C Thisjcabinet may bej'of .-,Wi thin.-..the cabinet is rigidlysecured a sup- -;pe rtin'g frame indicated Qasa whole by F. This framemay conveniently be cast or molded as a single member of suitable metal,such as alumimum, and it consists of a ring 29 supported on.

a pair of legs 30 which are firmly fastened to frame 14 adapted toreceive-the mouth of the;

horn, as will presently be made clear. Itgoes without saying that thecabinet 'as'a whbleis designed and finished as a beautiful piece ofhousehold furniture in which 'all mechanism'is' concealed fromview.

. Within thecabinet is mounted a sound-,ampli; fying horn indicatcdas.awhole-by H. This horn is-so constructedas to provide a maximum lengthof sound passageina minimum space. To this end. the horncomprises arear-section 15, a front .section- -16,- and aninnensection consistingof a pair-of lateral branch tubes 17 and ,18. As, seen in Fig. 2,;thesebraneh; tubes are substantially ;.U -shaped,- terminating in inner arms17 and. 18' respectively. -The,br anch tubes 17.

and 18 form a Y -connection with the front horn section 16 as shown inFig.1. The rear section 15 of horn H extends upwardly along the. backwall of the cabinet andthen curves forwardly untilit terminates in abelleshaped mouth 19,-whichfit-s into the correspondingly shaped frame14 at the front of the cabinet. If desired, theouter edge 29} as bymeans of a clamping ring32, secured by screws 33, or in any otherpractical way. Dia- The ring 29 may be provided with integral radialarms. 29 to increase the rigidity of the frame. A cone diaphragm I) issecured at its edge to ring phragm D may be constructed of any materialsuitable for; acoustic purposes, such as moistureproof-paper, parchment,sheet metal and the like.

Al though I have shown the diaphragm circular, it-rnay;b e of any otherdesign capable of giving properacoustic .response. For instance, suchdiaphragms can begiven various forms of ellipticalshapes. It will benoticed that the legs 30 of, supportihg.. f rame F straddle the U-shapedportion-.1 5 1Gj of the horn, so that the cone diaphragm is mountedbetween curved portions of the' horn. In "the. particular constructionshown in. Figs. 1- 4, the diaphragm D is sup ported inthe space'betweenthe lateral tubes 17 and 18, and between the upper and lower turns ofthe horn.' ,.Thus, it is seen that the diaphragm andits support do notdemand any more .space than the horn itse1f requires, thereby proofmouth 19, may be surroundedby a ring of felt or other sound-deadeningmaterial. In the prac-' tical construction of the horn, it is convenientto make sections 15 and-16 separate and unite them I by asuitabletight-fitting joint 20.- The parts 'may be housed in enclosethe' horn.

ducing'a constructionof great compactness that a cabinet just big enoughto .Th'e amplifying'horn H is connected at its two inner ends with apair of diaphragms 34 and 35.

16, 17 and 18 of the,horn maybacast, orv molded as a singlemembenwhichis rigidly securedfin,

the cabinet by any practical means..=,In the drawings I have shown thefront section 16 restj-j ing on the recessed block 21, to which-it isfirmly, secured by a strap 22 fastened to the. base of the,

cabinet. The block 21 is preferably of wood 'or other material whichdoes not, transmit acoustic vibrations, and a ring 23 of felt or likematerial -may be interposed between strap 22 and horn section 16. Thebranch tubes 17; and 18 are secured to the sides 11 of the cabinet bystraps 24,

which hold these tubes against recessed blocks 25. The rear section 15of; the-horn is secured to the back wall 12 of casing C by a strap 26,

which holds the horn .against a block 27, as f previously described inreference to block 21 and horn section 16.

It will thus beseen that the horn H is rigidly supported within thecabinet and is acoustically suitable fastening means. -sions 40 and 42are adapted to be axially ad- ,Diaphr'agm 34 communicates with tone arm17 and diaphragm 35 is similarly connected with tone arm 18; In order tofacilitate assembling of the diaphragms on their respective tone arms, Imeunt' the dia-phragms on a frame or casting indicated as a whole by E,which consists of a pair of rings 36 and 37 connected by arms 38.Diaphragm 34is seated on ring 36 and is'rigidly held in position byachambered disk or shallow casing 39 havinga tubular extension 40 adaptedto fit tight into the free end of tone arm 17. Likewise, diaphragm 35 issecured on ring 37 by a chambered disk or shallow casing 41, which isprovided-with a tubular extension 42 adapted to fit snugly into the freeend of tone arm 18. The disks or casings 39' and 41 are secured to theadjacent rings of frame E by screws-43 or other The tubular extenjustedin their respective tone arms and they are insulated from its walls.,The horn sections are 4 so shaped that they constitute a sound passageofprogressively increasing cross-sectional area from the inner end of arms17', and-18' to the mouth 19. This sound passage is of;.,sufiicientlength to give the proper amplification of sound waves entering theinner end of the :horn. Ow-

as will-readily be appreciated-by an inspection-of Figs. 1--4-.-The-horn maywbe built of metallic secured in adjusted position byset-screws 44 or otherwise. In assembling this part of the mechanism,thetubular extensions 40 and 42 are first inserted in their respectivetone arms'and then the framework-E'carrying the two diaphragms isinserted'between the disks'39 and i1, which are then-secured to therings of frame E. The

slidableadiustment of the'tubular extensions 40 ing to the constructionofthe h0m,- thiS:1Ong

be described. After the disks 39 and 41 have been secured to frame E,and after the latter has been axially-adjusted into-proper position,theset screws. are-tightened. If necessary. or deslrable, tight-fittingthrust collars of metal maybe.

inserted in the space between the-disks 39 and 41 and .the annular edges,46 oi.-tone.iarms 17' and 1,83;-

will be=clear from Diaphragms 34-,an d=3 5;-1are centrallyconnected ,arod 47 0f suflicient rigidity to:vibr ate--axnetic path. It'will'be seenfrom Fig. 5 that the -L-shaped pole pieces 54 and are secured to themagnet in-symmetrical or balanced position, so that the magnetic fieldflux will divide evenly (or .substantiallyso) '-between the two arms ofeach Figs.- 3 and 4"- withoutadditionalillustration.v Y

ially without buckling onmtherwise deforming.-

erates most eflicientlyfirEPmduin the middle register, Thelargediaphragm p, wl iich -requires no horn amplifier, tends tozacce'ntuatethe lower register of the musical-scale So it will beunderstoodthatdiaphragms 34,.35japd 1), whensimultaneously,-operated;=(as;will presentlybe de-,,

scribed), give .a sound reproduction; in which all tones of themusicaliscale are, brought; out with substantially uniform -intens ity,-irom the high est notes of the treble to the-deepest notes of therbass. .The correct design of the three dia Phragms lies withinthe skillof :the acoustic-em:

I gineer and need not be dweltupon here in detail.

.At. this point I would" call attention to the fact .that tone. arms 11'and 18 are oi substantially equal length, so that the soundwavesinitiated By arranging these diaphragms in. horizontal- ,planes, asshown in Figs. 3 and 4, I secure -a Fig. 4) This suggested arrangement,however,-

pole piece in passing-from one magnet-pole to the other. The dimensionsof pole pieces 54 and 55 are so' calcula'ted that they are traversed bythe magnetic'flux 'below'thepoint of saturation. It

will be-understood that the pole pieces 54 and 55 .are made ofmagneticmaterial having a high permeability; suchas soft-steel andcertain grades of --iron-which -arewell-known to those skilled in theelectrical art. Poleipieces 54 and 55 terminate at opposite-ends ii'ilateral lugs or extensions 57 and 58,.whichprovidea'rpairof airgaps59and 60 of equalpredetermined-width. .A bell-crank armature, indicated-asa whole by A is mounted on a bearinglpin. 61 symmetrical relation to thepole pieces 54 and 55. In the present instance. the bearing pin,61 iscarried bya non-magnetic block 62; which is-nrmly secured to pole piece54 in the :right-angledncornerthereof .(seeFig. 5). The

bell-crank;armature A, which is of soft steel or iron having.highmagnetic permeability. consists ofvapair of-right-angled arms 63and 64. The normal position of thearmature is such that the arms6Ii-.--64 extend centrally through airgaps .5.96.0. The rod 47, whichconnects diaphragms 34 and 35 as previously explained, passes through ascrew-threaded hole 65 at the outer end of arm by-the diaphragms 34 and.35 will pass simulta-..

neously into the .front."section 16- of,,the horn 64, and;a pairof nuts66 maintain the connection -;between rod .47and=arm 64 in rigidcondition during thevibrationsof-the armature. The arm 63 of armatureAis-connected to the center of cone diaphragm Diby arod or other stiffconnecting .membero'l, which is tightly held to arm 63 by a pair of-nuts68. Owing to the very small vibra ,tionsofthe armature, the ends of arms63 and 64 may berigidly'connected to the rods 47 and 6'7,

I ls within;.the:scope of. my, invention and. .will be,

understood without the tration;

I-now come to the eietataagtei gtichamsni for simultaneously operating,the three die-- phragms 34, 35 and-Din accordance with currentvariations in a controlling circuit. There is a magnet M formaintaining-a practically constant magnetic field of predeterminedstrength. This magnet may be of the permanent type,- orit may be anelectromagnet Dliovidedwith one or more coils traversed by asubstantially constant current of the requisite magnetizing strength. Asbest shown in Fig. 4, the supporting frame F is provided with a-bracketor block 49,which may conneedeot additional illuse havesuiiicientresiliency or elasticity to take care veniently be formed integral withone of; the cross- I position on block=49. The-.constructionof magnet}netic }spr ing metalgaresecured to pole piece 54 (as by screws.-, 72)and hold the coils firmly in in Figs 5, 6 and 8, to whichzreference,willmow be had. The. body of the magnet bent laterally,

arms 29 of the frame. q Screws 50 or other fastening means securelyholdthe magnet Minpropen -of.- the armature at that point.

of the slightly curved travel of the armature ends.

Bymeanspitheserigid connections, all lost motion is eliminated, wherebythe efiiciency and sensitiyeness of the instrument are increased. Itisassumed of course, that the supporting pivot 61 for thearrnatureprevents loose play or lost motion The inherent resiliency .oidiaphragms 34, 35 and D normally holds the armature midway Qf themagnetic air- ,gaps, asshown in Fig. 5, without the need of a separatecentering and restoring spring.

.-The ..operation of armature A is controlled by a pair oi coils -69 .and 70, which are mounted on and between the right-angled arms of polepieces ,54 and; 5 5. Qlamps 71, preferably of non-mag- I M and theattached pole pieces is best illustrated at 51 andterminates in an-Lshapedpolar exten-;-

sion 52. The other polar extension,53, isin line with .the main body ofthe magnet and may be of rectangular shape, as shown in Fig. 5. Themagnet is so designed that the polar terminals or. extensions 52 and 53have substantially the same cross-sectional area, so that the. fiuxdensity through these-extensions may be uniform. To the polar ends ofmagnet ,M are secured two -positlon.,..'Ifhe arms pf the armature passcen- ,trally';through the coils. In Fig.5 the coils are diagrammatieallyrepresentedby dotted outlines, soas not to obscure the drawing. I mayuse a pairofnon-magnetic plates 73 to hold the pole L-shaped polepieces54 and 55 .by meansof screws 56 or other fastening devices. Thesescrewsare preferablyof the-same magnetic material as the magnet, so as toreduce the reluctance ofthe magpieces 54 and 55in properlyspacedrelation before attaching them to the magnet. The plates 73.-may be ofbrass, oraluminum, and they are connected toth e pole pieces by screwsor other- .wise. ,In this-way the pole pieces, the armature and thetwomagnetizing coils constitute a unit which is. assembled before beingsecured to the magnet. The coils 69 and 70 are preferably connected inseries so as to act like a single coil in a circuit ofv variableelectric impulses. It will volition.

70. are ,disposed symmetrically with respect to 1 produce .vibrationthereof the right-angled armature A, whereby the magnetizing-effect ofthe cells is uniformly distributed through the armature. It goes withoutsaying that, the coils are so wound and connected that ..their magneticeffect at. any instant is cumulative.- That'is-to say; the two coils actlike a single coil to polarize. the armature in such a \vaythat. when-anorth pole is'formed at one end. a south poleis formed at the other endof extensions 57 and. 58 act-upon-the armature to derstood.

diaphragm is used for the horn. In this construction, theamplifyinghornH' consists of an upper section .74, an intermediateU"-shaped secand 78, so as to constitute a closed sound passage ofprogressively increasing cross-sectional area. .The horn is rigldlysuppo'rted 'in upright position by clamps or straps '79, which may besimilar to the straps 22- and -26 I previously referred to. If foundnecessary'or desirable, the" inner end of horn section 76'may' be bracedagainst vibrations by a' suitable bracket 80, which has a' pair of armsstraddling the horn section '74 and secured to the back'wall 12' of thecasing. To the'inner end 'ofhorn H is secured a shallow cylindricalcasing 81 carryinga diapliragm 82. A frame I fl wh'ich'may be consideredsimilar to frame F and therefore needs no further descriptiorr carries acone diaphragm D similar to'diaphr'agm D. -Diaphragm D is provided atthe center with a stiff-rod 83 which carries at its free end an armatureplate-or bar 84. v

As seen from Figs. 9 and 10. the diaphragm 82 and armature 84 aresubstantially parallel, and

between these two parts is arranged electromagnetic mechanism forsimultaneously operating the diaphragms. This mechanism is of novelconstruction and comprises one-ormore' magnets M firmly secured to lugsor-bracket's 85 projecting from an arm 86 of frame F. Screws 87 or otherfastening devices, hold the magnets firmly in position. In the presentinstance I employ a pair of circular permanent-magnets held to Thesemagnets," which constitute in effect a single-'ma'gnetjhre'" position,so that the mouth of the horn is at the gether by screws or pins 88.

provided with polar projections 89 and 90. As best shown in Fig. 10,these polar projections are separated or spaced at their free endsto'form legs 89 1 of polar legs 89' and '90; It is cl ear'from Fig.-

10 that the normal field 'fiux does not pass through the coils 93 and94, and the function of these coils is to polarize thepole pieces 91 and92. Diaphragm 82 and armature-84 of cone diaphragm D are arranged at theopposite ends in a manner wellu'ri- '-by theelectromagnetic mechanismabove de- There remains'to be describedthe' modifica'-"- tion shownin-Figs; 9-13, in' which only one' To promote not be necessary to showanycircuit connections for, the coils. because such circuits are wellunderstoodand do not form part of my present inof polepieces 91 and 92,and in such close proximity-- thereto as to be "readily actedupon by thevariable strength of the magnetic field'at the pole pieces. I '--Thediaphragm 82 may either be of magnetic material, or itmay benon-magnetic (as of aluminum or aluminum alloy) and carry a magnetic'arrnature'82': Instead of making the armature 82 as a separate piece ofiron or soft steel, I prefer to form the; same on the diaphragm by anelectrolytic deposit of iron. whichis held in intimate molecular contactwith the body of the diaphragm,

as I have attempted to indicate roughly in Fig. 13. This coating ofelectrolytically deposited iron need only be a thin circular plating atthe center of'the diaphragm, so that it adds very little weight te -thediaphrag'mand therefore does not appreciably increase its inertia.

Inthe operation of the diaphragms 82 and D' scribed, the currentvariations through coils 93 and 94-at' any instance affect theopposite-ends of the pole pieces 91 and 92 reversely. That is to say,when the polar ends N and S are strength ened,-the opposite polar'ehds Nand S are simultaneously weakened, and vice versa. Consequently. thediaphragms82 and D'- are simultaneously operated slightly out of step."The practical result of this dephased' operation of the diaphragms is anacoustic reproduction of rich tonal duality; H

simplicity in the drawings-I have shown the enclosing cabinet C as asubstantially rectangular'box. *In the practical .design of such acabinet, it is desirable to avoid sound pockets by eliminating"rectangular corners. I have attempted to indicate this roughly in'Figs.2, 3 and 9, wherethe dotted lines 95 represent panels or partitions fordirecting the inwardly projected sound vibrations of diaphragm D or 'D'out of the open front of the cabinet. It is evident that the baffleboard'95 'by reflecting sound waves out of the cabinet amplifies thereproduction of the cone D: "In fact, the enclosed space in which thecone is supported acts like anamplifying chamber of which the curvedsound-reflecting board 95 forms the back wall. This chamber, therefore,increases the final'tone volumeand improves the quality of reproduction.'These sound-reflecting panels may either be arran'ged'withinthe outerwalls of the cabinet, or they may form part of the outer cabinetstructure. Thefront of the cabinet is closed 1 by an ornamental coveradapted to transmit freely the vibrations of the cone diaphragm. Such acover, which I'have indicated diagrammatically by dotted lines 96 inFigs. 2, 3 and 9, may be a thin porous fabric, or a grille, or anyotherdesign of cover suitable for the purpose. Although I haveillustrated cabinet C in upright top, it goes without saying that thecabinet may be so designed that any of its sides may constitute thebase. Therefore, when -I speak of the top and bottom or front and rearof the cabinet, I use'those'terms in a relative sense only, and not byway of restriction. The two constructions shown in the drawings are tobe considered as merely illustrative examples embodying my invention,which includes various other modifications within the scope of theappended claims.

What I claim as my invention is: 1. A loudspeaker comprising a hornhaving curved portions arranged to provide a sound passage of requisitelength in a comparatively small space, a cone diaphragm mounted outsideof said horn in a space between the curved portions of said horn, adiaphragm connected 'with the inner end of said horn, and mechanism' foroperating both diaphragms. I

2. A loudspeaker comprising 'a'horn which consists of a main bodyportion having a'pair of 'lattending toward each other at their innerends, a diaphragm connected to the inner end of each branch tube, acone'diaphragm' mounted in the space wthin said branch-tubes, andmechanism for operating all of said diaphragms.

3. A combined horn and cone speaker in which the cone diaphragmis'supported 'in a' space outsideof said horn and bounded by portions ofthe horn and mechanism for' oper'a'ting the' hornand cone diaphragm.

4. In a loudspeaker, the combination of a horn coiled back upon itself;'a cone diaphragm mounted outside of said horn in the space between thecoils of said horn, a diaphragm connected to the inner 'end of said'horn and arrangedadjacent to said cone diaphragm, and-means outside ofsaid horn for Qp'eratingsaid diaphragms.

5. A loudspeaker comprising'a'base;'a' frame secured to said base, acone diaphragm mounted on said frame, a horn' supported on said baseindependently of said frame, said horn having a U- shaped portionarranged substantially at right angles to said frame and extending onopposite sides thereof, a diaphragm at the inner end of said horn, andmeans for operating said diaphragms.

6. A loudspeaker cabinet containing a horn and a cone diaphragm, a framesecured in said cabinet for supporting said cone diaphragm, meansindependent of said frame for securing said horn in rigid position, saidhorn having a curved portion extending on opposite sides of said conediaphragm, the latter being arranged outside of said horns, a smalldiaphrgam connected with the inner end of said horn, and means foroperating both diaphragms, one side of said cabinet being open for theemission of sound from said horn and cone diaphragm.

7. A combined horn and cone speaker comprising a cabinet open at thefront, a cone diaphragm supported in said cabinet substantially parallelwith said open front, a horn supported in said cabinet in such positionthat its mouth terminates at the top portion of said open front, saidcone diaphragm being arranged outside of said horn, a diaphragm at theinner end of said horn, and means for operating said diaphragms.

8. A combined horn and cone speaker comprising a cabinet open at oneside for the emission of sound, a cone diaphragm supported in saidcabinet substantially parallel with said open side, sound-reflectingwalls arranged within said cabinet back of said cone diaphragm fordirecting sound waves into the open air, a horn supported in saidcabinet and having a diaphragm at its inner end, said cone diaphragmbeing supported outside of said horn, and means for operating saiddiaphragms.

9. A loudspeaker comprising a cabinetopenat the front, a curved hornmounted in said cabinet, said horn having a downwardly extending frontsection and an upwardly extending rear section which terminates in amouth at the top of the cabinet, a curved inner section of the hornbeing arranged between said front and rear sections and extendingforwardly to join said front section, said horn sections forming anamplifying .diaphragm' at the free 'end of said inner section,

a conediaphragm supportdin-said cabinet out- .side-of'n'said hornbetweed'said innerand front horn sections in a position 'substantiallyparallel with'the front=of the 'eabinetg' and means in saideral' branchtubes connected thereto, said branch tubes being approximately U-shaped;and excabinet for operating s'aid diaphragmsiwapair-of 'lateral branchtubes, said main body portion -having a downwardly extending frontsection and an upwardly extending rear section which terminates ina'rnouth at the top of'the cabinet, said branch" tubes beingarranged=between said front and rear sections and uniting 4 1withsaid'frontseetion, a pair of diaphragms con- -nected to the' free'ends or 'said branch tubes; a .cone' diaphragm supported'in said cabinetbef tween said branch tubes and 'be'twen' the top and bottom-parts of'the main body-portion- 'of said horn, said cone diaphragmbeing-positioned in a plane: substantially-at" right angles to'the planeof the main 'body p'ortion of said hom," and mechanism in the cabinet 4for operatingall of said diaphragms; I

' 11-; In loudspeaker mechanism; a pair of-diaphragms supported in'substantially parallel relation, a third diaphragm supportedsubstantially at right angles to said pair of diaphragms, and

means connected to all three diaphragms fornected to the ends of saidbellcrank, and means for vibrating said bellcrank about its pivot.

13. A loudspeaker comprising a cabinet open to the outer air, anamplifying horn mounted in said cabinet, a diaphragm for sending soundwaves through said horn, a loudspeaking diaphragm supported in saidcabinet independently of said horn and wholly outside thereof, andmechanism arranged between said diaphragms outside of said horn forsimultaneously operating the same.

14. A loudspeaker comprising a cabinet open to the outer air, a framerigidly supported in said cabinet, a loudspeaking diaphragm carried bysaid frame, a horn supported in said cabinet independently of saidframe, said loud speaking diaphragm being supported outside of saidhorn, a diaphragm acoustically connected with said horn, and mechanismfor simultaneously operating said diaphragms.

15. A loudspeaker comprising three diaphragms so constructed as toaccentuate, respectively, the higher register, the middle register andthe lower register of tones, one of said diaphragms being a conediaphragm requiring no amplifier, a horn for amplifying the vibrationsof the other two diaphragms, means for supporting said cone diaphragmoutside of said horn, and mechanism for simultaneously operating allthree diaphragms.

16. A combined horn and cone speaker in which fyingchamber for saidlarge diaphragm.

20. Aloudspeaker comprising acabinet having an .open front and acurvedback wall, a horn mounted in saidcabinet, a diaphragm at'the inner endof said.horn,-a cone diaphragm support ,ed in said cabinetindependentlyof said horn, and

actuating-means for said diaphragms, said curved back,wall reflectingsound waves from said cone diaphragm out of the cabinet to amplify thereproduction.

' 21. A loudspeakercomprising a cabinet, an ampliryinghorn mounted insaidvcabinet, a pair of diaphragms-connected with said horn, saiddiaphragms being constructed to accentuate the higher register andthemiddle register of the musical scale, a cone diaphragm supported insaid approximately through an angle of.180 at a substantial distancefrom each side of thev outlet opening of said bell portion.

23. A horn comprising a bell portion having inlet andoutlet openings,two sound passages communicating with said inlet opening, said passagesextending laterally in opposite directions approximately at right anglesto a m'edial plane through the axis of the bell portion and curvingthrough an angle of at least 180 at a substantial distance Irom eachside of the outlet opening of said bell portion, said last mentionedbend being of such radius that said sound passages do not intersect theplane of the mouth of the bell portion.

ADOLPH A. THOMAS.

